Hi bradraddad , thank you for trusting us with your problem.
There are a couple of things that can cause this. The first thing to check is a binding throttle cable. Remove the cable from the throttle and see if it makes a difference.
The next thing to check is a vacuum leak. A large leak will fool the engine computer and give you the exact same result as holding the throttle open. The computer will add more fuel to compensate for the extra air and the RPMs will be much higher than normal. Visually check all the vacuum hoses. If you do not see a any that are torn, collapsed, or broken then use carburetor spray to look for a leak. This can be dangerous so you need to be careful. Use the straw and spray lightly at the vacuum hoses, intake gaskets, and throttle body gaskets. The RPMs will change when you have found the leak. Be very careful to avoid the ignition wires and the exhaust so you do not start a fire.
Thanks again and let me know if you need any more help!
Auto Service Technician
ASE Master Tech, ASE Advanced engine performance